中英文字符串截取类

<?php

/**
* description：中英文字符串截取
* @author ：SunsCheung
* @date：2015-09-24
*/
class Helper{
public static function truncate_utf8_string($string, $length, $etc = '...')
{
$result = '';
$string = html_entity_decode(trim(strip_tags($string)), ENT_QUOTES, 'UTF-8');
$strlen = strlen($string);
for ($i = 0; (($i < $strlen) && ($length > 0)); $i++)
{
if ($number = strpos(str_pad(decbin(ord(substr($string, $i, 1))), 8, '0', STR_PAD_LEFT), '0'))
{
if ($length < 1.0)
{
break;
}
$result .= substr($string, $i, $number);
$length -= 1.0;
$i += $number - 1;
}
else
{
$result .= substr($string, $i, 1);
$length -= 0.5;
}
}
$result = htmlspecialchars($result, ENT_QUOTES, 'UTF-8');
if ($i < $strlen)
{
$result .= $etc;
}
return $result;
}
}